Low platelet count after Afoxolaner (NexGard) in dogs

152 reports to the FDA describe low platelet count in dogs given Afoxolaner. That is 0.3% of all reports for this medicine, compared with 0.2% across reports for all dog medicines.

152Reports
64%Marked serious
14%Recovered
20%Died or euthanised
9 daysTypical onset
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How soon it started

Same day
19 18%
1–2 days
23 22%
3–7 days
8 7.5%
1–4 weeks
28 26%
Over a month
28 26%

How the animals did

Recovered
20 13%
Recovered with lasting effects
1 0.7%
Still unwell when reported
45 30%
Died
11 7.2%
Euthanised
19 13%
Not known
56 37%

Problems reported at the same time

Age of the animals

Under 1 year
11
1–3 years
36
4–7 years
51
8–11 years
39
12+ years
13

About this medicine

Afoxolaner kills fleas and ticks; given as a monthly chewable.

Products with this ingredient include NexGard. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

In 2018 the FDA alerted owners and vets that isoxazoline products have been associated with neurologic reactions such as muscle tremors, wobbliness (ataxia) and seizures, including in animals with no history of them.

Questions owners ask

Can Afoxolaner cause low platelet count in dogs?
152 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?
In half of the reports with dates, it started within 9 days of the first dose.
What should I do?
Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Low platelet count with similar medicines

All reported side effects of Afoxolaner in dogs · Medicines most reported with low platelet count